There's a phenomena that I've just invented where, whenever an actor reaches a certain age, he starts to only promote new films by banging on about his most iconic role. Let's call it Harrison Ford Syndrome, named after the actor who's made a point of filling every junket since about 1995 with a series of noncommittal mumbles about possible Indiana Jones sequels.

And now it seems as if Bruce Willis has fallen prey to the phenomena, too. Although he's busy ostensibly publicising Cop Out, what Willis is actually doing is informing the world of his intention to make Die Hard 5 as soon as he can. And, unsurprisingly, the typical internet reaction has been one of barely-suppressed outrage. He's selling out, they say. He's sullying the memory of the original, they say. He's so old that Die Hard 5 will have to feature a plot that largely revolves around a Werther's Original theft in a haemorrhoid cushion factory, they say. But they're wrong.

Bruce Willis should absolutely make Die Hard 5. In fact, there's a fairly strong argument for Bruce Willis to make nothing but Die Hard sequels for the rest of his life. Bear with me here. Die Hard 4 – or Die Hard 4.0 or Live Free Or Die Hard or whatever it was called – might have lacked the soul of the first film, but it was still a perfectly serviceable action movie. Plus it had a flying car that totally exploded a helicopter. That has to count for something, right? My point is this – there's still life in the old dog yet.

And let's face facts here. Even if Die Hard 5 doesn't reach fruition, Willis is still going to keep making Die Hard films. They'll just be called different things. Surrogates was Robot Die Hard, Cop Out is Buddy Die Hard and The Expendables will be Die Hard v Rambo. IMDb even states that Willis is about to make a movie adaptation of Kane & Lynch, a videogame notable only for looking a bit like the 1996 Die Hard game. If Bruce is going to keep starring in films like this, surely it makes sense for him to double the box-office takings by pulling on a dirty vest and saying "Yippee-ki-yay" during them.

Worse still – what if, rather than Die Hard 5, Willis decides to make more films that are nothing like Die Hard? What if he makes something as hopeless as Perfect Stranger or as toe-curling as Colour of Night again? Would you be able to live with yourself if that happened? Maybe. Would you watch them? History says you wouldn't.

Most of all, though, Die Hard 5 has to happen because it's the only way we'll get a Die Hard 6. Remember that each film has become successively less claustrophobic, with a skyscraper giving way to an airport giving way to a city giving way to the internet. Willis has stated his intention to continue this trend by taking Die Hard 5 "worldwide", which can only mean one thing. Logic dictates that, if there's ever a Die Hard 6, it would have to be set in outer space. Look me in the eye and tell me you don't want to see John McClane shooting a vaguely German-looking alien in the face with a machine gun. You can't, can you?

Stuart Heritage: After throwing Alan Rickman off a skyscraper, Bruce Willis, as John McClane, is back to tackle a super-nasty ex-Special Forces bad guy and generally fire guns. But hey, it's Christmas…